JP6511775B2 - Reverberation sound addition device - Google Patents

Description

  The present invention relates to an apparatus for adding a signal indicating reverberation to an input sound signal.

  There is a technique of simulating an acoustic characteristic of a predetermined space and adding a signal (reversing signal) indicating a reverberation of the space to an input acoustic signal (input signal). In this technique, an output signal obtained by adding a reverberation signal to an input signal is supplied to a speaker, and a sound with reverberation is emitted from the speaker.

  One of the physical factors that affect the auditory impression of the reverberation is the temporal density (hereinafter referred to as the sound density) of the sounds that make up the reverberation. An auditory impression corresponding to the sound density of the reverberation is referred to as the density of the reverberation. For example, if the sound density of the reverberation sound is high, it will be a dense and clogged reverberation sound, and if the sound density of the reverberation sound is low, it will be a reverberation sound that is sparse and sparse.

Japanese Patent Laid-Open No. 2000-069598 Unexamined-Japanese-Patent No. 2004-212797

  The sound density of the reverberation differs depending on the type and content of the input signal, the acoustic characteristics of the space, and the like. For this reason, the sound density of the preferred reverberation is different. For example, as reverberation to be added to the sound of an instrument that produces strong shorts of attack such as drums, reverberation with a relatively high sound density is preferred, but for sounds such as a classical performance in a concert hall with a long reverberation As the reverberation to be added, reverberation with a relatively low sound density is preferred. For this reason, there is a demand for controlling the sound density of the reverberation sound to an appropriate size according to the type and content of the input signal, the acoustic characteristics of the space, and the like.

  As an example of a technique for controlling the sound density of reverberation, a technique for increasing the generation density of reverberation signals using an all-pass filter is disclosed in Patent Document 1 (see paragraph 0008 of Patent Document 1). In the reverberation addition circuit including the comb filter and the all-pass filter disclosed in Patent Document 1, although the reverberation can be generated while increasing the sound density of the reverberation, the impulse response (the acoustic characteristic of the predetermined space A physical quantity representing a time response, which is hereinafter referred to as “IR”, is not a convolution method, and therefore acoustic characteristics of a predetermined space can not be reproduced.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a reverberation addition apparatus capable of controlling the sound density of reverberation while simulating the acoustic characteristics of a predetermined space. To aim.

  The present invention adds noise by adding noise generation means for generating predetermined noise, impulse noise generation means for generating impulse noise consisting of an impulse train having random time intervals, and the noise and the impulse noise. The addition noise generation means for generating, the impulse response generation means for generating a correction impulse response by multiplying the addition noise and the amplitude characteristic of the impulse response representing the acoustic characteristic of the space, and the correction impulse for the input sound signal And an impulse response convolution means for convoluting and outputting the response.

  According to the present invention, a corrected impulse response is generated from addition noise obtained by adding impulse noises composed of impulse trains having random time intervals, and the corrected impulse response is convoluted into an acoustic signal. Thereby, the signal after being convoluted has a random time interval corresponding to the impulse noise. For this reason, the sound density of the signal after being convoluted changes. Therefore, according to the reverberation addition device, the sound density of the reverberation can be controlled.

It is a block diagram which shows the structure of the reverberation addition apparatus 1 which is one Embodiment of this invention. It is a figure which shows the concept of the impulse noise production | generation process of the impulse noise production | generation part 60 of the reverberation addition apparatus 1 of the same. It is a figure which shows the structure of the signal processing part 30 of the reverberation addition apparatus 1 of the same. FIG. 6 is a diagram showing a configuration of an acoustic calculation unit 100 that is a basic configuration of the direct sound calculation unit 101, the initial reflection sound calculation unit 102, and the rear reverberation calculation unit 103 of the signal processing unit 30. It is a figure which shows the structure of the uncorrelated IR convolution filter 105 of the signal processing part 30. FIG. It is a conceptual diagram which shows the content of the process which the uncorrelated IR production | generation part 310 of the uncorrelated IR convolution filter 105 performs. It is a flowchart which shows the content of the process which the uncorrelated IR production | generation part 310 performs. It is a figure which shows the example of the time expansion-contraction process which the same uncorrelated IR production | generation part 310 performs by the time expansion-contraction part 450 by zone. It is a figure which shows the example of the time expansion-contraction process according to the same zone. It is a figure explaining the modification (1) of this invention. It is a figure explaining the modification (3) of this invention. It is a figure explaining the modification (5) of this invention. It is a figure which shows the structure of the signal processing part 30B of the modification (6) of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment
FIG. 1 is a block diagram showing the configuration of a reverberation adding apparatus 1 according to an embodiment of the present invention. The reverberation adding apparatus 1 includes a control unit 10, an input / output interface (hereinafter referred to as an input / output I / F) 20, a signal processing unit 30, a storage unit 40, a noise generation unit 50, an impulse noise generation unit 60, and these configurations. It includes a bus 70 that mediates the exchange of data between elements. The reverberation addition apparatus 1 has one input system to which an acoustic signal is input, and has a plurality of (N in this embodiment) output systems to which output signals are output. Speakers 80 are connected to the reverberation addition device 1 as many as the number of output systems. The reverberation addition device 1 is a device that adds a signal (reversing signal) indicating reverberation to the input acoustic signal (input signal) and outputs the signal to the speaker 80. The reverberation sound addition device 1 is used, for example, in a theater or a movie theater. The plurality of speakers 80 connected to the reverberation addition device 1 are installed, for example, on the wall of a theater or a cinema.

  The control unit 10 is, for example, a CPU (central processing unit). The control unit 10 functions as a control center of the reverberation addition device 1 by executing a program (not shown) stored in the storage unit 40. The storage unit 40 is a storage device including a non-volatile storage unit such as a flash ROM and a volatile storage unit such as a random access memory (RAM). The non-volatile storage unit stores a program to be executed by the control device 10. The program is, for example, a program that instructs the signal processing unit 30 on various parameters for processing an input signal. Further, an impulse response (IR) is stored in the non-volatile storage unit. The IR is, for example, an impulse response obtained by measuring in a predetermined space (for example, a theater or a cinema). The IR may be an impulse response obtained by simulating (calculating) the propagation characteristics of the reflected sound in a predetermined space. Alternatively, it may be an impulse response obtained by appropriately combining, editing, and processing IRs obtained by actual measurement or simulation (calculation). The point is that any impulse response that represents the acoustic characteristics of a predetermined space may be used. In this embodiment, IRs measured at representative sound sources and sound receiving points in space are stored in the non-volatile storage unit. The volatile storage unit is used as a work area for executing a program in the non-volatile storage unit.

  The input / output I / F 20 includes an operation element such as a mouse and a display device such as a display. The operator of the input / output I / F 20 sends a signal corresponding to the operation by the user to the control unit 10. Further, the display device of the input / output I / F 20 displays information according to the control of the control unit 10 on the screen. The user can specify the aspect of the space and the like by the input / output I / F 20. For example, the user operates the operation element to specify the position information of the wall surface of the space.

  The noise generation unit 50 is a noise generation unit that generates a predetermined noise. The predetermined noise is stationary noise, for example, noise such as white noise having a constant level and a wide band frequency component. The noise generation unit 50 of the present embodiment generates a plurality of (N) different types of noise that are independent for each output system. More specifically, the noise generation unit 50 generates a plurality (N) of noises that are uncorrelated (or less correlated). The noise generated by the noise generation unit 50 has a time length similar to that of IR, and is, for example, about 10 seconds. The generated noise is delivered to the signal processing unit 30.

  The impulse noise generation unit 60 is a means for generating impulse noise composed of a series of impulses generated at random time intervals. Specifically, the random time interval in the present embodiment is determined under control according to a predetermined probability. That is, this impulse noise is impulse noise consisting of an impulse sequence having a predetermined time interval. FIG. 2 is a diagram showing the concept of impulse noise generation processing of the impulse noise generation unit 60. As shown in FIG. FIG. 2A shows a probability density function representing the probability density of the time interval generated by each impulse in the impulse train. The impulse noise generation unit 60 generates impulses by generating each impulse in accordance with the probability density function shown in FIG. Here, the time interval of the impulse on the horizontal axis in FIG. 2A is the time interval until the next impulse occurs, and the probability density on the vertical axis is the probability of generating the impulse in that time interval. Specifically, as an example, the probability of generating the next impulse in a 5 ms time interval is 1/8, the probability of generating the next impulse in a 10 ms time interval is 1⁄4, 15 ms The probability of generating the next impulse in the time interval is set to 1/8, etc.

  FIG. 2B is a diagram illustrating a method of generating an impulse train using the probability density function of FIG. 2A. FIG. 2B shows function values obtained by integrating the probability density function of FIG. 2A with a time interval of 0 to a predetermined value. In the impulse sequence generation method illustrated in FIG. 2B, the impulse noise generation unit 60 sequentially and uniformly generates random numbers between 0 and 1 (specifically, pseudo random numbers) according to a clock or the like. Contains. The value of the random number generated by the random number generation unit corresponds to the integral value of the probability density of FIG. 2 (B). The impulse noise generation unit 60 determines the value of the time interval from the integral value of the probability density corresponding to the value of the generated random number. Then, based on the determined time interval, an impulse train generation unit generates an impulse. Thus, impulses corresponding to the probability density function of the initially set time interval can be sequentially generated at the time interval of the predetermined probability. Here, although the time interval of the generated impulse changes every moment, it is governed by the above-mentioned probability density function, and the average time interval of the impulse is kept at a predetermined value (value determined by the probability density function) Be In practice, impulse generation processing is performed so that, for example, about 1000 impulses are included in an impulse sequence in a time of about 0.1 seconds to 20 seconds. Therefore, the average time interval of the impulses is set to about 0.1 ms to 20 ms. The generated impulse noise is delivered to the signal processing unit 30.

  The signal processing unit 30 illustrated in FIG. 1 is, for example, a DSP (digital signal processor). The signal processing unit 30 is means for performing processing for adding a reverberation signal to an input signal. The signal processing unit 30 has a plurality of (N in this embodiment) output terminals. Each of the plurality of output ends of the signal processing unit 30 is connected to the N speakers 80. The power amplifier for driving the speaker 80 is not shown.

  FIG. 3 is a diagram showing an entire configuration of the signal processing unit 30. As shown in FIG. As shown in FIG. 3, the signal processing unit 30 includes a direct sound calculation unit 101, an initial reflection sound calculation unit 102, a back reverberation calculation unit 103, an acoustic characteristic approximation filter 104, and a non-correlated IR convolution filter 105. , Multipliers 106, 107 and 108, and adders 109 and 110, respectively. One input signal is input to the signal processing unit 30 through the input terminal 115, and N different signals are output through N output systems.

  Generally, a sound reaching a sound receiving point where a listener is located from a sound source such as a musical instrument in a certain space is composed of a direct sound and a reverberation sound. Also, the reverberation sound is composed of an early reflection sound and a rear reverberation sound. In the present specification, the direct sound refers to a sound that reaches the sound receiving point directly from the sound source. The reverberation sound refers to a sound that follows a direct sound and is reflected by a boundary (a wall, a ceiling, etc.) in space to reach a sound receiving point. The early reflection sound refers to an early reflection sound with a small number of reflections among sounds that are reflected at the boundary in space and reach the sound receiving point, and particularly refers to a reflection sound of about 1st to 2nd order. Of the sounds that are reflected by the wall of the acoustic space and reach the receiving point, the back reflection sound refers to the reflection sound that has more reflections than the initial reflection sound, and in particular, the third to sixth reflection sound Say that. The n-th (n is 1, 2, 3...) Reflected sound means sound that reaches the sound receiving point after being reflected n times at the boundary in space. In addition, the orders described above as second order, third order, sixth order, and the like are merely examples, and other orders may be used.

  The acoustic characteristic approximation filter 104 shown in FIG. 3 is a means for giving the timbre of the space to be simulated. Specifically, the acoustic characteristic approximation filter 104 is a filter that indicates the attenuation characteristic of the sound according to the distance of the propagation path of the initial reflection sound, or the acoustic characteristic of the wall surface when the initial reflection sound is reflected by the wall surface of space. It is a filter etc. which show the corresponding attenuation characteristic.

  The direct sound calculation unit 101, the initial reflection sound calculation unit 102, and the rear reverberation calculation unit 103 are means for calculating the propagation characteristics of the direct sound, the initial reflection sound, and the rear reverberation, respectively. More specifically, the direct sound calculation unit 101 applies the result of simulating the propagation characteristic corresponding to the direct sound propagation path in space to the input signal input from the input terminal 115, and connects the multiplier 106. It is a means to distribute to a plurality of output lines. The initial reflection sound calculation unit 102 applies the result of simulating the propagation characteristics corresponding to each propagation path of the initial reflection sound to the input signal input from the input end 115 through the acoustic characteristic approximation filter 104 and performing multiplication. It is a means to distribute to a plurality of output lines connected to the unit 107. The rear reverberation calculation unit 103 applies the result of simulating the propagation characteristic corresponding to each propagation path of the rear reverberation to the input signal input from the input end 115, and connects the uncorrelated IR convolution filter 105. It is a means to distribute to a plurality of output lines. The number of output lines of the direct sound calculation unit 101, the number of output lines of the initial reflection sound calculation unit 102, and the number of output lines of the rear reverberation calculation unit 103 are the same. The output lines of the direct sound calculation unit 101, the initial reflection sound calculation unit 102, and the rear reverberation calculation unit 103 correspond to the output system of the reverberation addition apparatus 1.

  The basic configurations of the direct sound calculation unit 101, the initial reflection sound calculation unit 102, and the rear reverberation calculation unit 103 are the same. Hereinafter, these basic calculation units will be referred to as a sound calculation unit 100. The sound calculation unit 100 includes, for example, a process of calculating propagation characteristics of reflected sound by a calculation method such as mirror image method or sound ray method, and a three-dimensional panning process such as a vector base amplitude panning (VBAP) method. The acoustic field calculation processing is performed. FIG. 4 is a diagram showing the configuration of the sound calculation unit 100. As shown in FIG. The sound calculation unit 100 includes a delay line 210, a filter 220, and a matrix unit 230. These units are means for performing correction according to the parameter instructed from the control unit 10 on the acoustic signal input through the input terminal 201.

  The delay line 210 is a so-called multi-tap delay. The delay line 210 transmits the acoustic signal input through the input end 201, and the signals delayed by different times are respectively transmitted from the plurality of taps Ti (i = 1, 2, 3,...) On the way It is a means to output, The signal output from each tap respond | corresponds to a direct sound and each reflected sound, respectively. Therefore, each of the direct sound calculation unit 101, the initial reflection sound calculation unit 102, and the rear reverberation calculation unit 103 has different numbers of taps Ti. The positions of the plurality of taps Ti (i = 1, 2, 3,...) In the delay line 210 (that is, the delay times of the signals output from the respective taps) are controlled by the control unit 10. Each corresponds to the delay time of the direct sound and each reflected sound.

  A multiplier 220 is provided downstream of each of the plurality of taps Ti (i = 1, 2, 3,...). The multiplier 220 is means for multiplying the sound signal output from the delay line 210 by a specific coefficient instructed by the control unit 10. The multiplier 220 is a means for reflecting the characteristic that the sound pressure level of the sound emitted from the sound source is attenuated according to the path length of the propagation path. For example, the multiplier 220 connected to the tap T1 executes multiplication processing that reflects the attenuation characteristics of the sound (in this case, direct sound) arriving at the sound reception point following the propagation path associated with the tap T1. Do. Specifically, the multiplier 220 multiplies a relatively small numerical value if the path length of the propagation path associated with the multiplier 220 is long, and multiplies a relatively large numerical value if the path length is short. And so on.

  The matrix unit 230 is a means for distributing the acoustic signal output from the multiplier 220 into a plurality of (N in this embodiment) output lines 242, and the number of multipliers 220 to be input (the direct sound calculation unit 101 has 1; The initial reflection sound calculation unit 102 has 2 and the rear reverberation calculation unit 103 has 4) × the number of output lines (N). The number of output lines 242 is the same as the number of output systems of the signal processing unit 30 (that is, the number of speakers 80). The matrix unit 230 will be described in more detail below. The matrix unit 230 includes a multiplier 231 and an adder 232 at each position where each input line 241 to which the signal output from the multiplier 220 is connected and each output line 242 cross. The multiplier 231 multiplies the signal input through the input line 241 by a predetermined coefficient instructed by the control unit 10 and outputs the product to the adder 232. The process of multiplying the predetermined coefficient performed by the multiplier 231 is a so-called three-dimensional panning process. That is, to the multiplier 231, an appropriate coefficient is given by the control unit 10 for each output system so that the sound (direct sound or reflected sound) indicated by the signal input to each input line 241 is localized at a predetermined position. Be By the processing by the multiplier 231, the direct sound and each reflected sound are appropriately simulated in the propagation direction from the sound source to the sound receiving point. The adder 232 supplies the sound signal output from the multiplier 231 to the output line 242.

  As described above, the sound calculation unit 100 is configured to perform processing on the sound signal for each assumed propagation path in a predetermined space. Hereinafter, a set of elements for processing an acoustic signal to simulate one propagation path will be referred to as a “characteristic control system 250”. In the example of FIG. 4, one characteristic control system 250 includes delay lines 210 (more specifically, one tap Ti portion) connected to one input line 241, one multiplier 220, and N multipliers 231. Become. The above is the configuration of the sound calculation unit 100. The acoustic calculation unit 100 is disclosed in Patent Document 2.

  Therefore, assuming that the characteristic control system 250 is one processing unit, in the direct sound calculation unit 101, the initial reflection sound calculation unit 102, and the rear reverberation calculation unit 103 in the present embodiment, in the basic sound calculation unit 100 described above, It can be said that the number of characteristic control systems 250 is different. That is, the direct sound calculation unit 101 has the characteristic control system 250 as many as the number of propagation paths of the direct sound, that is, one. The initial reflected sound calculation unit 102 calculates the number of all propagation paths of the initial reflected sound, that is, the number obtained by adding the number of all propagation paths of the primary reflected sound and the number of all propagation paths of the secondary reflected sound. Only has a characteristic control system 250. For example, in a rectangular parallelepiped three-dimensional space, the number of propagation paths of primary reflected sound is six, and the number of propagation paths of secondary reflected sound is eighteen. The number is 24 pieces. The rear reverberation calculation unit 103 calculates the number of all propagation paths of the rear reverberation, that is, the number of all propagation paths of the third reflection and the number of all propagation paths of the fourth reflection and the fifth reflection. There are as many characteristic control systems 250 as the number obtained by adding the number of all propagation paths of and the number of all propagation paths of the sixth-order reflection sound.

  Next, the uncorrelated IR convolution filter 105 will be described. The uncorrelated IR convolution filter 105 is provided at the output stage of the rear reverberation calculation unit 103 (more precisely, the matrix unit 230 of the rear reverberation calculation unit 103). FIG. 5 is a diagram showing the configuration of the uncorrelated IR convolution filter 105. As shown in FIG. The uncorrelated IR convolution filter 105 has a reverb 300 for each output line 242 of the rear reverberation calculation unit 103. The reverb 300 includes an uncorrelated IR generator 310 and a convolution processor 320.

  The uncorrelated IR generation unit 310 is a means for generating uncorrelated IRs uncorrelated with each other among the reverbs 300. Impulse noise is supplied from the impulse noise generation unit 60, noise is supplied from the noise generation unit 50, and IR is supplied from the storage unit 40 to the uncorrelated IR generation unit 310. The uncorrelated IR generation process performed by the uncorrelated IR generation unit 310 will be described in detail later. The convolution processing unit 320 is a unit that performs processing of convoluting the uncorrelated IR generated by the uncorrelated IR generation unit 310 with the acoustic signal output from the rear reverberation calculation unit 103. The convolution processing unit 320 outputs the acoustic signal generated by the convolution processing as an acoustic signal indicating the rear reverberation.

  Next, referring back to FIG. The output stage of the direct sound calculation unit 101 is provided with a multiplier 106 for each output line 242. The multiplier 106 is means for multiplying an acoustic signal (sound signal indicating direct sound) output from the output end of the direct sound calculation unit 101 by a specific coefficient instructed by the control unit 10. A multiplier 107 is provided for each output line 242 at the output stage of the initial reflected sound calculation unit 102. The multiplier 107 is means for multiplying the sound signal (sound signal indicating the initial reflected sound) output from the output end of the initial reflected sound calculation unit 102 by the specific coefficient instructed by the control unit 10. At the output stage of the uncorrelated IR convolution filter 105, a multiplier 108 is provided for each output line 242 of the rear reverberation calculation unit 103. The multiplier 108 is means for multiplying the acoustic signal filtered by the uncorrelated IR convolution filter 105 (the acoustic signal indicating the rear reverberation) by a specific coefficient designated by the control unit 10. The multipliers 106, 107 and 108 play the role of adjusting the volume balance of the direct sound, the early reflection sound, and the rear reverberation sound according to the coefficient instructed from the control unit 10.

  The adder 109 is a means for adding the acoustic signal output from the multiplier 106 and the acoustic signal output from the multiplier 107 for each output line 242. That is, the adder 109 plays the role of adding the direct sound and the initial reflection sound for each output system. The adder 110 is a means for adding the sound signal output from the adder 109 and the sound signal output from the multiplier 108 for each output line 242. That is, the adder 110 plays a role of adding the direct sound, the initial reflection sound, and the rear reverberation sound for each output system. Each of the plurality of adders 110 outputs an output signal obtained by adding a reverberation signal to an input signal to the speaker 80 of the output stage.

  Next, the uncorrelated IR generation processing performed by the uncorrelated IR generation unit 310 of the uncorrelated IR convolution filter 105 will be described in detail. FIG. 6 is a conceptual diagram showing the contents of the non-correlated IR generation process performed by the non-correlated IR generation unit 310. As shown in FIG. FIG. 7 is a flowchart showing the contents of the uncorrelated IR process. First, the control unit 10 transmits the impulse noise generated by the impulse noise generation unit 60 to the uncorrelated IR generation unit 310 of each reverb 300. In parallel, the control unit 10 transmits a plurality of (N in this embodiment) non-correlated noises generated by the noise generation unit 50 to the non-correlated IR generation units 310 of the respective reverbs 300. Furthermore, in parallel, the control unit 10 reads out the IRs stored in the storage unit 40 and transmits them to the uncorrelated IR generation units 310 of the respective reverberations. Hereinafter, one non-correlated IR generation unit 310 of the respective uncorrelated IR generation units 310 for each reverb 300 will be described based on FIGS. 6 and 7 as an example.

  The uncorrelated IR generation unit 310 to which the impulse noise is input performs multiplication processing of multiplying the impulse noise by the coefficient g1 by the multiplier 401 shown in FIG. 6 (FIG. 7: SA110). Similarly, the non-correlated IR generation unit 310 having received the noise performs a multiplication process of multiplying the noise by the coefficient g2 (SA120). Thereafter, each non-correlated IR generation unit 310 performs an addition process of adding the impulse noise multiplied by the coefficient g1 and the noise multiplied by the coefficient g2 by the adder 403 (SA130). This produces additive noise. That is, the multipliers 401 and 402 responsible for multiplication processing of the coefficients g1 and g2 and the adder 403 responsible for addition processing of the signals after the multiplication processing add impulse noise to each of a plurality of noises to perform a plurality of additions. It is addition noise generation means for generating noise. Since the generated additive noise contains impulse noise, it has a signal density corresponding to the impulse train of impulse noise. Moreover, since the addition noise includes uncorrelated noise, the addition noise generated by each reverb 300 becomes a signal uncorrelated with each other.

  The coefficient g1 and the coefficient g2 are respectively set to arbitrary values by the instruction of the control unit 10. The values of the coefficients g1 and g2 determine the magnitudes of the impulse noise and the noise and the addition ratio thereof. For example, when the coefficient g2 is made larger than the coefficient g1, the ratio of noise becomes higher than the impulse noise, and the sound density of the reverberation sound becomes high. In this case, the sound emitted from the speaker 80 is a sound with a high sense of density of the reverberation. On the other hand, when the coefficient g1 is made larger than the coefficient g2, the ratio of impulse noise becomes higher than the noise, and the sound density of reverberation sound becomes low. In this case, the sound emitted from the speaker 80 is a sound with a low sense of density of the reverberation. That is, in the present embodiment, the control unit 10 controls the values of the coefficient g1 and the coefficient g2 independently to change the sense of density of the reverberation sound.

  Next, the non-correlated IR generation unit 310 causes the section division unit 410 to divide the addition noise into a plurality of (five in FIG. 5) sections along the time axis (SA140). Although each of noise and impulse noise is shown as being divided into a plurality of sections along their time axis in FIG. 6, this is because it is intuitively easy to understand. Then, the noise and the impulse noise are added by the adder 403 and then divided into a plurality of sections.

  Next, the non-correlated IR generation unit 310 causes the section division unit 430 to divide the IR into a plurality of sections (SA150). The process of the section dividing unit 430 is the same process as the section dividing unit 410. Specifically, the section dividing unit 430 divides the IR into a plurality of sections along the time axis. The number of IR intervals is the same as the number of addition noise intervals.

  Next, the non-correlated IR generation unit 310 performs window function processing and fast Fourier transform by the fast Fourier transform (FFT) unit 420 (SA 160). It will be described in more detail. The non-correlated IR generation unit 310 extracts addition noise of two consecutive intervals in the addition noise divided by the interval division unit 410. At this time, the non-correlated IR generation unit 310 extracts two sections at a time along the time axis from the head of the addition noise. The uncorrelated IR generation unit 310 multiplies the extracted addition noise of the two sections by the window function. The window function is, for example, a Hanning window function. The uncorrelated IR generator 310 performs fast Fourier transform on the added noise multiplied by the window function. As a result, a signal Hnoise obtained by frequency-converting the extracted added noise in each of the two sections is sequentially generated.

  Next, the uncorrelated IR generation unit 310 performs window function processing and fast Fourier transform by the fast Fourier transform (FFT) unit 440 (SA 170). The process of the fast Fourier transform unit 440 is the same process as the fast Fourier transform unit 420. More specifically, the non-correlated IR generation unit 310 extracts IRs of two consecutive intervals in the IRs divided by the interval division unit 430. At this time, the non-correlated IR generation unit 310 extracts two sections in order from the top of the IR along the time axis. The uncorrelated IR generation unit 310 multiplies the window function by the extracted two sections of IR. The window function is, for example, a Hanning window function. The uncorrelated IR generator 310 performs fast Fourier transform on the IR multiplied by the window function. Thereby, the signal which frequency-transformed IR of the said extracted 2 area every is produced | generated sequentially.

  Next, the non-correlated IR generation unit 310 performs the time-dependent time expansion / contraction process by the time-dependent time expansion / contraction process unit 450 on the acoustic signal after the fast Fourier transform by the fast Fourier transform unit 440 (SA180). The band-based time expansion / contraction process is a process of performing time expansion / contraction processing for each frequency band. This time expansion / contraction process is a process for expanding (or compressing) the reverberation time of the rear reverberation. FIG. 8 is a diagram showing an example of the time expansion / contraction process in the band-wise time expansion / contraction processing unit 450. FIG. 8 (A) shows before time expansion and contraction. FIG. 8B shows a state after time expansion and contraction, in which FIG. 8A is expanded by 1.5 times in the direction along the time axis. The horizontal axis of FIGS. 8A and 8B is time, and the vertical axis is amplitude. For example, by performing time expansion by 1.5 times, the second (m = 2) time position from the leftmost time position (reference position (m = 0)) before time expansion (FIG. 8A) The amplitude of corresponds to the third (m = 3) time position from the reference position (m = 0) after time extension (FIG. 8 (B)), and the reference position before time extension (FIG. 8 (A)) The amplitude of the fourth (m = 4) time position from (m = 0) is at the sixth (m = 6) time position from the reference position (m = 0) after time extension (FIG. 8 (B)). It corresponds to the situation. Such expansion and contraction in the direction along the time axis can be realized by, for example, simple linear interpolation or polynomial interpolation. As described above, the time expansion / contraction process of the per-band time expansion / contraction unit 450 is an expansion / contraction process of the time transition of the amplitude for each frequency bin in the acoustic signal after fast Fourier transform in the direction along the time axis.

  FIG. 9 is a diagram showing an example in which the time expansion and contraction process is performed for each band. The horizontal axis of FIG. 9 is the frequency, and the vertical axis is the scaling factor of the time expansion and contraction with respect to the reverberation time. In the example of FIG. 9, the magnification factor of time expansion and contraction is 1 in the frequency bands f2 to f3. That is, in the frequency bands f2 to f3, the reverberation time does not change before and after the time expansion / contraction process. On the other hand, at frequencies lower than the frequency f2 (in particular, frequencies lower than the frequency f1), the time expansion factor is lower than 1 and at frequencies higher than the frequency f3 (especially higher than the frequency f4) The scaling factor is higher than 1. That is, at frequencies lower than frequency f2, the time expansion and contraction process compresses the time to shorten the reverberation time, and at frequencies higher than frequency f3, the time expansion and contraction process extends time and the reverberation time is longer There is. Therefore, the reverberation time is separately set for each band, for example, changing the low and high reverberation times (low dump and high dump) without changing the mid-range reverberation time, for example, by performing band-specific time expansion and contraction processing. It can be changed.

  Next, as shown in FIG. 6, the non-correlated IR generation unit 310 causes the synthesis processing unit 460 to generate the signal Hnoise obtained by the fast Fourier transform unit 420 by the band-wise time expansion / contraction unit 450. The signal H which is the result of the combining process is output (SA 190). Note that the combining processing by the combining processing unit 460 is performed each time the section dividing unit 410 and the section dividing unit 430 output the above-described two sections of each of the addition noise and IR. By the above-described synthesis processing, it is possible to reflect the characteristic of the time response of the addition noise on the amplitude (so-called frequency characteristic) of the frequency response of IR. Here, since the wide-band stationary noise and the impulse noise composed of an impulse sequence are added to the addition noise, the reverberation sound obtained by the convolution of the signal H obtained by the synthesis processing corresponds to the addition noise. Sound density is reflected. Further, since the phase characteristic of the addition noise is stored in the signal H obtained by the synthesis processing, the signals H of the respective reverberations 300 also become uncorrelated signals.

  Next, the non-correlated IR generation unit 310 sequentially performs inverse Fourier transform (IFFT) on the signal H obtained by the synthesis processing unit 460 by the inverse Fourier transform (IFFT) unit 470 (SA200). Next, the non-correlated IR generation unit 310 determines whether fast Fourier transform has been performed for all time ranges of IR (SA210). If the determination result in step SA210 is No, the non-correlated IR generation unit 310 shifts the range of two consecutive sections to be extracted backward by one section (SA220), and returns to step SA160. Then, the non-correlated IR generation unit 310 repeats the processing of steps SA160 to SA210. In this repetition, in step SA160, the addition noise shifted backward by one interval is extracted to perform window function processing and fast Fourier transformation, and in step SA170, the IR shifted backward in one interval is extracted to perform window function processing Perform fast Fourier transform. As described above, the non-correlated IR generation unit 310 performs short-time Fourier transformation over the entire range of the IR and the addition noise while overlapping one section every repetition of steps SA160 to SA210.

  Then, if the determination result in step SA210 is Yes, the non-correlated IR generation unit 310 combines a plurality of inverse Fourier transform results obtained by repeating steps SA160 to SA210, and ends the process (SA230). In this manner, the uncorrelated IR generator 310 generates uncorrelated IRs uncorrelated with each other for each output line 242 of the rear reverberation calculation unit 103. In consideration of the processing content of the uncorrelated IR generation unit 310 as described above, the uncorrelated IR is an impulse response obtained by correcting the IR representing the acoustic characteristic of the space by the addition noise, and the synthesis processing of the uncorrelated IR generation unit 310 The unit 460 can be said to be means for generating an impulse response corrected by multiplying the addition noise and the amplitude characteristic of IR representing the acoustic characteristic of the space.

  As described above, the reverberation addition apparatus 1 of the present embodiment includes a unit (specifically, the direct sound calculation unit 101) that generates an acoustic signal indicating a direct sound, and a unit that generates an acoustic signal indicating an initial reflection sound. (Specifically, the initial reflection sound calculation unit 102 and the acoustic characteristic approximation filter 104) and means for generating an acoustic signal indicating the rear reflection sound (specifically, the rear reverberation calculation unit 103 and the uncorrelated IR convolution filter 105) And separately. The means for generating an acoustic signal indicating direct sound does not perform filtering such as the acoustic characteristic approximation filter 104. As a result, direct sound with less deterioration in sound quality can be obtained. The means for generating an acoustic signal indicating an initial reflection sound performs filtering by the acoustic characteristic approximation filter 104 in addition to the delay and three-dimensional panning. As a result, an initial reflected sound with a sense of direction being maintained and an initial reflected sound in which the timbre of space is reproduced can be obtained. The means for generating an acoustic signal representing the rear reverberation performs a filtering process that convolves the uncorrelated IR in addition to the delay and the three-dimensional panning. For this reason, the acoustic signal indicating the rear reverberation is uncorrelated for each output line connected to each of the plurality of speakers. The uncorrelated IR is a modified impulse response in which the characteristic of the time response of the additive noise is reflected on the amplitude (so-called frequency characteristic) of the IR frequency response. The additive noise is generated by adding impulse noise consisting of an impulse train having a predetermined probability time interval. For this reason, the acoustic signal indicating the rear reverberation has a sound density corresponding to the sound density of the additive noise. Therefore, in the reverberation addition apparatus 1, the sound density of the acoustic signal indicating the rear reverberation can be controlled by changing the addition ratio of the addition noise to control the sound density of the addition noise. From these, in the reverberation addition device 1, the sense of direction and the tone of IR are maintained, and there is a sense of spreading, and a rear reverberation having an appropriate sense of reverberation density can be obtained. Therefore, according to the reverberation addition apparatus 1, the sound density of the reverberation can be controlled while simulating the acoustic characteristics of a predetermined space to reproduce the acoustic characteristics of the space. Also, since the uncorrelated IR is generated from one IR, it is possible to generate a reverberation that reflects the acoustic characteristics of a predetermined space.

Other Embodiments
As mentioned above, although one Embodiment of this invention was described, another embodiment can be considered to this invention. For example:

(1) The reverberation sound addition device is not limited to a mode in which reverberation sound simulating the acoustic characteristics of space is added to the sound emitted and received from the nondirectional sound source, and the sound emission from the directivity sound source is not limited It is also possible to add a reverberation that simulates the acoustic characteristics of space to the sound received and received. For example, as shown in FIG. 10, each propagation path according to an angle θd between an axis of the sound source in the front direction and the sound receiving point and an angle θr between the axis of the virtual sound source in the mirror image method and the sound receiving point It is the condition that the attenuation parameter etc. in the above are multiplied by the weighting factor. In this aspect, reverberation in consideration of the directivity of a sound source (for example, the directivity of a musical instrument) can be added.

(2) The reverberation sound addition device is not limited to a mode in which reverberation sound simulating the acoustic characteristics of space is added to the sound emitted and received from the sound source whose position is fixed, and it is emitted from the moving sound source A reverberation sound obtained by simulating the acoustic characteristics of space may be added to the received sound. In this aspect, the control unit 10 can be realized by sequentially acquiring the information of the position of the sound source and the position of the sound receiving point and sequentially determining the parameters of each element of the acoustic calculation unit. In this aspect, reverberation can be added even if the position of the sound source changes in real time.

(3) The reverberation addition apparatus may be configured to add a reverberation that simulates the acoustic characteristics of space to the sound that is emitted and received from a sound source that changes in directivity direction while moving. For example, as shown in FIG. 11, there is a case where a sound source having directivity turns 90 degrees while advancing toward the front direction. This aspect can be realized by combining the aspect of the movement of the sound source described above and the aspect of the sound source having directivity. In this aspect, for example, it is possible to add the reverberation of space to the speech of the person who speaks while turning 90 degrees while walking toward the front direction.

(4) The reverberation addition apparatus is not limited to a mode in which reverberation that simulates the acoustic characteristics of the space is added to the sound reaching the sound receiving point whose position is fixed, and the sound reaching the moving sound receiving point It may be an aspect of adding reverberation that simulates the acoustic characteristics of space. Also in this aspect, it can be realized in the same manner as the above-described aspect of moving the sound source. In this aspect, reverberation can be added even if the position of the sound receiving point changes in real time. Of course, it may be a mode of simulating the case where both the sound source and the sound receiving point move. In addition, the sound source in the aspect in which the sound receiving point moves may be nondirectional or may have directivity.

(5) In the reverberation addition apparatus 1 of the above-described embodiment, the acoustic characteristic approximation filter 104 is provided at the front stage of the initial reflection sound calculation unit 102. However, as shown in FIG. 12, an acoustic characteristic approximation filter 104A may be provided at a stage subsequent to the initial reflected sound calculation unit 102. In this aspect, the acoustic characteristic approximation filter 104A is provided for each output line 242 of the initial reflected sound calculation unit 102. In this way, the control unit 10 can designate different parameters to the respective acoustic characteristic approximation filters 104A for each output line 242. Therefore, in this aspect, an initial reflection sound in which the timbre of the space is reproduced in more detail can be obtained.

(6) The signal processing unit 30 according to the above-described embodiment has only one input end to which an input signal is input. However, the signal processing unit may have a plurality of input ends, and different input signals may be supplied to each of the plurality of input ends. FIG. 13 is a diagram showing a configuration example of a signal processing unit 30B having two input ends 201a and 201b. The signal processing unit 30B of FIG. 13 includes an initial reflected sound calculation unit 102a and a rear reverberation calculation unit 103a connected to the input end 201a, and an initial reflected sound calculation unit 102b and a rear reverberation calculation unit connected to the input end 201b. And 103b. The signal processing unit 30B simulates primary to secondary reflected sound (initially reflected sound) on the first input signal supplied from the input end 201a in the initial reflected sound calculation unit 102a, and the initial reflected sound calculation unit A simulation of primary to secondary reflected sound (initial reflected sound) is performed on a second input signal supplied from the input end 201b at 102b. Next, the signal processing unit 30B performs filtering on the acoustic characteristic approximation filter 104B after adding the acoustic signal output from the initial reflected sound calculation unit 102a and the acoustic signal output from the initial reflected sound calculation unit 102b. . Further, in parallel to these processes, the signal processing unit 30B causes the rear reverberation calculation unit 103a to generate third to sixth reflected sounds (rear reverberation) with respect to the first input signal supplied from the input end 201a. The rear reverberation calculation unit 103b simulates third to sixth reflections (rear reverberation) on the second input signal supplied from the input terminal 201b. Next, the signal processing unit 30B adds the acoustic signal output from the rear reverberation calculation unit 103a and the acoustic signal output from the rear reverberation calculation unit 103b, and then performs the filtering process of the uncorrelated IR convolution filter 105B. Do. With such a configuration, reverberation signals can be added to each of the first input signal and the second input signal.

(7) The reverberation addition apparatus 1 of the above embodiment has a plurality of output systems. However, the reverberation addition device may have one output system. In this aspect, the noise generation unit generates only one noise, and the uncorrelated IR generation unit generates only one corrected impulse response. Also in this aspect, since the impulse response corrected from the additive noise and the IR is generated as in the above embodiment, the sound density of the reverberation can be controlled as in the above embodiment.

(8) In the reverberation sound addition apparatus 1 of the above embodiment, the sound density of the addition noise is changed by adjusting the addition ratio of the impulse noise and the noise. However, the reverberation addition apparatus may change the sound density of the addition noise by changing the time interval of the impulse train in the impulse noise generation unit 60. For example, according to the instruction of the control unit 10, the probability density function is changed to change the time interval of the impulse train. This aspect is applicable, for example, when moving from a different space (as a specific example, when going out of a tunnel). Further, the reverberation addition apparatus may make the mode of change of the time interval of the impulse train different for each sound source. Also, the reverberation addition apparatus may make the aspect of the addition ratio of impulse noise and noise different for each sound source. In these aspects, appropriate reverberation can be added according to the type of sound source.

(9) In the reverberation sound addition apparatus 1 of the above embodiment, the control unit 10 changes the sound density of the addition noise. However, an operator such as a knob for adjusting the sound density of the additive noise operated by the user is provided in the impulse noise generation unit 60, and the sound density of the additive noise is changed according to the operation of the operator. May be At this time, the addition ratio of impulse noise and noise may be changed by the operation of the manipulator, the time interval of the impulse sequence may be changed, or both the addition ratio and the time interval may be changed. .

(10) The uncorrelated IR generation unit 310 of the above embodiment combines the amplitude characteristic and the phase characteristic of each of the plurality of addition noises with the amplitude characteristic of IR to generate a plurality of uncorrelated IRs that are mutually uncorrelated. Was. However, the uncorrelated IR generation unit may combine each of at least phase characteristics of each of the plurality of addition noises and the amplitude characteristic of IR to generate a plurality of uncorrelated IRs uncorrelated with each other. This is because by using at least the phase characteristic of the additive noise, the plurality of generated impulse responses become uncorrelated with each other.

(11) Although the non-correlated IR generation unit 310 of the above-described embodiment performs the band-based time expansion and contraction process 450, the band-based time expansion and contraction process 450 may be omitted.

(12) The noise (stationary noise) generated by the noise generation unit 50 in the above embodiment may be noise other than white noise, such as Gaussian noise or pink noise.

(13) In the reverberation addition apparatus 1 of the above embodiment, the third to sixth reflection sounds are simulated to generate an acoustic signal indicating a rear reverberation. However, the simulation for the rear reverberation is not limited to the third to sixth reflections. For example, the third to fifth reflections may be simulated to generate an acoustic signal indicating a rear reverberation, or the third to seventh reflections may be simulated to generate an acoustic signal indicating a rear reverberation. You may. The order of the reflected sound for generating the acoustic signal representing the rear reverberation may be determined in consideration of the acoustic characteristics of the predetermined space to be simulated and the sound density of the reverberation to be controlled.

(14) In the above embodiment, the addition noise generation means, the impulse response generation means, and the impulse response convolution means are realized by the electronic circuit (specifically, the signal processing unit 30). However, for example, the computer may function as addition noise generation means, impulse response generation means, and impulse response convolution means by causing the control unit to execute a reverberation addition program. In addition, the computer may function as a noise generation unit and an impulse noise generation unit by causing the control unit to execute a reverberation addition program. In this case, the reverberation addition program may be traded as installed in the reverberation addition apparatus, may be separately traded as stored in a computer readable storage medium, or may be networked. It may be traded by downloading.

  DESCRIPTION OF SYMBOLS 1 ... reverberation sound addition apparatus, 10 ... control part, 20 ... input / output I / F, 30 ... signal processing part, 40 ... storage part, 50 ... noise generation part, 60 ... impulse noise generation part, 70 ... bus, 80 ... Speaker 100 100 sound calculation unit 101 direct sound calculation unit 102 initial reflection sound calculation unit 103 rear reverberation calculation unit 104 acoustic characteristic filter 105 uncorrelated IR convolution filter 106, 107, 108 ... multiplier, 109, 110 ... adder, 115, 201 ... input end, 116 ... output end, 210 ... delay line, 220 ... multiplier, 230 ... matrix section, 231 ... multiplier, 232 ... adder, 241 ... Input line, 242: Output line, 250: Characteristic control system, T: Tap, 300: Reverb, 310: Uncorrelated IR generator, 320: Convolution processor, 401, 402 ... Adder, 403 ... adder, 410, 430 ... section dividing unit, 420,450 ... fast Fourier transform unit, 450 ... band by the time expansion and contraction processing unit, 460 ... synthesis processing section, 470 ... inverse fast Fourier transform unit.

Claims (5)

Noise generation means for generating predetermined noise;
Impulse noise generating means for generating impulse noise consisting of impulse trains having random time intervals;
Addition noise generation means for generating addition noise by adding the noise and the impulse noise;
Impulse response generation means for generating a corrected impulse response by multiplying the addition noise by an amplitude characteristic of an impulse response representing an acoustic characteristic of space;
Impulse response convolution means for convoluting the modified impulse response with the input acoustic signal and outputting the signal;
A reverberant sound addition device characterized by having. The addition noise generation means
First multiplication means for multiplying the impulse noise by a first coefficient;
Second multiplying means for multiplying the noise by a second coefficient;
Addition means for adding the output of the first multiplication means and the output of the second multiplication means to generate the addition noise;
The reverberation adding device according to claim 1 , characterized in that:   The reverberation sound addition device according to claim 1 or 2, wherein the impulse noise generating means generates impulses at time intervals according to a predetermined probability density function to generate the impulse train. The noise generating means generates a plurality of noises that are uncorrelated with each other,
The addition noise generation unit adds the impulse noise to each of the plurality of noises to generate a plurality of addition noises.
The impulse response generation means multiplies each of the plurality of addition noises by the amplitude characteristic of the impulse response to generate a plurality of corrected impulse responses uncorrelated with one another.
The impulse response convolution unit convolutes each of the plurality of modified impulse responses generated by the impulse response generation unit into the input acoustic signal, and outputs the convoluted signal. The reverberation sound addition apparatus according to claim 1. Computer,
Noise generation means for generating predetermined noise;
Impulse noise generating means for generating impulse noise consisting of impulse trains having random time intervals;
Addition noise generation means for generating addition noise by adding the noise and the impulse noise;
Impulse response generation means for generating a corrected impulse response by multiplying the addition noise by an amplitude characteristic of an impulse response representing an acoustic characteristic of space;
Impulse response convolution means for convoluting the modified impulse response with the input acoustic signal and outputting the same
Reverberation sound addition program characterized in that it functions as.

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